<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Document</title>
  </head>
  <body>
    <script>
      var obj = 123;
      console.log(obj.toString());	// 输出结果：123
      obj = [1, 2, 3];
      console.log(obj.toString());	// 输出结果：1,2,3
      obj = function () { };
      console.log(obj.toString());	// 输出结果：function () {}
    </script>
  </body>
</html>